A Comparative Study of Water- and Benzene-Saturated Mesoporous Silicas by $^{1}H$ NMR Spectroscopy

H-1 NMR investigations have been carried out ion water- and benzene-saturated mesoporous sillicas with a wide range of pore sizes (13-42 Angstrom). The freezing point of the bound water increases with the pore size, approaching that of bulk water at large pore sizes. With large pore sizes, there is more than one transition due to the bound water species. The benzene-saturated samples show a behavior similar to that of water-saturated samples, although the freezing point depression is significantly greater. The pore size distribution generally becomes broader with the increase in pore size. The original Kelvin equation is satisfactory to estimate the pore radii both in the case of water and benzene-saturated samples